1. Field of the Invention
The present invention relates generally to a vehicle distribution system and, more particularly, to a vehicle distribution system for providing a stable supply or distribution of vehicles to a plurality of ports within an area so as to keep up with ride demands at each of the ports.
2. Description of the Relevant Art
Where vehicles need to be distributed among a plurality of ports within an area in response to ride demands generated at each of the ports, some ports may lack vehicles to meet their ride demands while others may have excess vehicles. In such a case, a vehicle distribution system may be devised to reallocate or redistribute surplus vehicles between ports to replenish shortages of vehicles at other ports.
According to the background art, one vehicle distribution system is designed to deal with vehicle shortages on a posterior basis. In other words, vehicles are reallocated when a shortage occurs and not in anticipation of a predicted shortage. It takes time to move surplus vehicles from one port to another. Therefore, if a new ride demand occurs while vehicle redistribution is under way, or if some vehicles left ports on their way to other ports before a redistribution process is initiated, a surplus or shortage of vehicles may occur again at any port upon completion of the redistribution. Such occurrences can cause passengers to be left wait on vehicles for extended periods of time, such that a preferred minimum waiting time for passengers cannot be observed in the face of varying ride demands.
One solution to the above deficiency may be for vehicles to be redistributed on the basis of predicted ride demand data. Illustratively, a system may be devised to distribute vehicles according to predicted ride demand data based on the number of existing vehicles at each of the ports, on the ride demands currently generated at the port in question, and on past statistical ride demand data regarding the port.
One example of that system is a vehicle demand predicting system disclosed in Laid-Open Japanese Patent Application No. Hei 9-153098. This vehicle demand predicting system utilizes the statistical data as raw data. This means that if the raw data differ from actual ride demands, the system is significantly affected by such variances. The result can be a vehicle distribution system of poor accuracy, with a large number of vehicles redistributed unproductively (as will be discussed in detail with reference to FIGS. 14 and 15). If the system redistributes vehicles while predicting ride demands using statistical data, the redistribution process should preferably be carried out with a minimum of wastefully redistributed vehicles, even if actual ride demands deviate from the statistical data.